Process for preparing organosilanes



Patented Oct. 9, 19 51 Lipscomb; W11

g'ton, DeL, assignors to E. I-

du Pont de Nemofirs & Company, Wilmington, Del., a corporation'of Delaware 7 V N Drawing.

containing at least one hydrogen on silicon. A further object is the provision of a process therefor; Other objects will appear hereinafter. 7

"These objects are accomplished by the follow} ing invention'wherein a halo'sila'ne having hydro gen and halogen on the one'silicon is reacted in' the liquid phase with a cycloalkenein the pres:

ence of a free'radical yield'ing catalyst or' of actinic light.

The 'free radical liberating' catalysts "which are particularly useful in initiating this reactionarecompounds having the general formula RXXR wherein R is a monov'alent organic radical. R is' a monovalent'organicradical or hydrogen; and X is an element of integral atomic numberof 7'to 8, i. e., oxygen or nitrogen. Thepreferred type of free radical-generating catalyst used in" the, process of this invention is" an' organic azb" compound wherein the azo, -N=N, gr'oup'is acyclic and bonded from both of the nitrogens to Particularly preferred" are" those azo compoundswherem both valences 'oftli'e' acyclic azo group "are attached to different car? difi'erent carbons;

bons which are non-aromatic, i. e., aliphatic or' cycloaliphatic; and at least one of which is ter ti'a'ry, which tertiary carbon has further-attached to it through another carbon a negative radical in which the three remaining valences of the lat ter carbon are satisfied by at least one element of atomic number 7 to 8 (nitrogen and/or oiiygem, i. e., the'nitrile, carbalkoxy; and carbon"- amide groups.

azonitriles are readily obtained and have high activity. Still morepreferred arethe symmet rical azocompounds having two tertiary carbons attached to the azo nitrogens and these negative groups attached to the tertiary carbons -sincef' they are active as catalysts at lower temperatures than the unsymmetrical compounds. These particular azo compounds are preferred since they- Carb'alkoxy groups in whichthe" alkyl group contains from one to six carbon atoms are preferred. The negative radical in general is neutral with respect to acidity; and of these, neutral radicals the nitrile is preferred sincethe' Application Serial-"No. 5507' 7 Claims? ('01. 26min) 1 are efiectiveinmataIyZing the reaction in react?! tare" is: liquid by carr ti'on-vessel's" constructed'of metal as W ll as; in glass or glassdined-metalz Another type of free radical genera'tings catalyst which iseffective in,

- glass or glass-linedequipmentbut which ismuch less effective in metal apparatus; is" thatof or ganic peroxygen'wcompounds: such* as benzoyl peroxide. In carrying outv the" reaction in the presence of actinic light it-'-isjpreferred to use light having; awaveflength of 3600 A or less. 7 H v j In a preferred method forcarrying out the process of this inventieni'am'ixture of a cycloalkene,-e: gr, cyclohexenaand a halosilane hayi at--1ea ned ogen; atom Join d to the: siliconatom; e-.-g trichlorosilane; is heated in the presence of a mall amount, e g,- from 0.5%; to "3%: of-jt iwe h n rz he r ac a s; f a ree rad lr vcatalysn ch: as an M0 9Qmpound o the :type: d fine -ab ve. oram xturer of two;oi suchazo compounds. The tempera ure got t e aet nid pendso h Part cu a reactants; and on the partiQl-llar' catalyst being; used. However,; temperatures ranging frQmi aboutfl0i C to-up' 1 20 C. are conveniently used: The time of heating should be; sufficiemily nearly to complete the generation of; ireegradicalsfrom the catalyst, andthis in turn depends on the half-life period Of-"the p'articuIar catalyst or catalyst mixture being employed. In general, periods" of 'tifril?rfi l rlgiing from one t6' seventeen A w 'uirs'raiigmg" I? to C. 'lhefreac ion ispre erably carried out under endants" t6 eiiclu'de masters," as] moisture? reacts es ny with the" amsnarist This is co nlfe' tly do Wh lithe reaction miX mgdll't th e're aotidii lfi aiacuonvessrfifitea'with a rflux' condns and by sweeping fout'the' aetibrispacewith nitrogeiiand'then eon'tinu n'gftlie heatirig at" flux temperature under. a shglit'fprsslir'lof d 'y" convenes-a1 methods s lle iq enet er b di nt whi his par icu es? ful when n. e eiynee catal e e n use 4: consists inheatingthe' mixture ofj-the cyclo ;alkene withlthe halosilanein the presence of the 3 azo catalyst in a closed reaction vessel such as a stainless steel or silver-lined steel reactor, under the autogenous pressure developed by the ingredients. In this embodiment the reactor is preferably agitated by mechanical means to obtain good agitation of the reactants.

Still another embodiment of this invention consists in contacting a cycloalkene with a halosilane and irradiating the mixture with ultraviolet light, i. e., light of wave length below 3600 A, for several hours. The reaction product is then isolated by conventional methods, such as fractional distillation.

The invention is further illustrated by the following examples in which the proportions of the ingredients are expressed in parts by weight unless otherwise specified.

Examplel 1, A solution of 50 parts of trichlorosilane, 20

parts of cyclohexene, 1 part of alpha,a lpha-azo- 3 diisobutyronitrile, and 1 part of l,1"-azodicyclo- Erample II 'A mixture of 50 parts of trichlorosilane, 20

parts of cyclohexene, and 2 parts of benzoyl peroxide is placed in a glass reaction vessel fitted with a condenser. After flushing out the reactor with nitrogen the solution is heated until it refluxes, under a nitrogen pressure of 50-60 cm. mercury above atmospheric pressure. Heating is continued for 14-hours under these conditions, the temperature of the reaction mixture ranging from 60 to 63 C. Thereaction mixture is then fractionally distilled and there 'is obtained 35' parts of cyclohexyltrichlorosilane, boiling at 203 C. This corresponds to a yield of 66%, based on the weight of cyclohexene employed.

Erampl e III "A mixture of 50 parts of trichlorosilane, 20 parts of cyclohexene, and 2 parts of alpha,alpha'- azobis(alpha,gamma dimethylvaleronitrile) is heated to refluxing temperature, 60-65 C., for 16 dialkyl and monoand diarylhalosilanes having hydrogen and halogen on the one silicon atom. Specific halosilanes which may be used include HzSiClz, HSiBrs, HSiFa, HzSiIz, HsSiCl C2H5SiI-IC12, (CH3)2SiHCl, CsI-IsSiHClz (CsH5) 2SiI-IC1. The process of the invention is generic to cycloalkenes including, in addition to the cycloalkene of the examples, cyclopropene, cyclopentene, cyclobutene, 1,5 cyclooctadiene, cyclooctatetraene, 1,3 cyclohexadiene, 1,4 dimethylcyclohexene, l-propylcyclohexene, l-methylcyclohexene and l-amylcyclohexene. Cycloalkenes which are particularly suitable in the process of this invention are those having from three to eight carbon atoms in the ring, and with hydrogen on at least one doubly bonded carbon. These cycloalkenes can also contain lower alkyl substituents (i. e., alkyl groups of one to five carbon atoms) on the cycloalkene nucleus. Thus cycloalkenes of three to eight annular carbons and three to eleven total carbons are particularly suitable.

30, to minimize side reactions and since the halo-' I rate,

hours under the conditions described in Example 7 II. After this period the reaction mixtureis' fractionally distilled and there is obtained '6 parts of'"cyclohexyltrichlorosilane, boiling at 44 C./2

mm. This yield corresponds to 36% "of theo-' retical, based on the amount of cyclohexene consumed in the reaction.

"The process of thi invention is generic to halosilanes having hydrogen and halogen on the one silicon. Particularly preferred are those halosilanes where the valences of thesilicon not satisfied by, i. e., bonded to,hydrogen and halogen are bonded to saturatedmonovalent hydrocarbon radicals. By saturated is meant free fromnon-aromatic unsaturation. Of these the saturated radicals aliphatic in character are particularly desirable'. The halosilanes useful in the process of thisinventionincludethe-'monoand The relative proportions of the cycloalkenes and halosilanes used in the practice of this invention can be varied over wide limits.

amounts, but since an excess of halosilane tends silane is readily recovered, it is preferred to use an excess of this reactant. A 50% excess of the halosilane is very suitable.

Example I illustrates the use of a mixture 3 of two particular azo compounds as catalysts in the process of this invention. However, other azo compounds of the type defined above, used either alone or in mixtures, are also effective. A mixture of two different azo catalysts having 40, different decomposition temperatures, i. e., tem- .decomposing at the lower temperature provides the necessary free radicals during the first stage later stages'of the reaction at the higher temper- 50 atures. Other azo compounds which are suitable for use in the practice of this invention,

either alone or in combination, include dimethyl,

diethyl, and dihexyl alpha,alpha'-azodiisobutyazobis (alpha-cyclopropylpropionitrile) alpha azobis(alpha,beta,beta trimethyl butyronitrile) alpha,alpha-azobis (alpha-cyclo- Y hexylpropionitrile) alpha,alpha'- azobis-(alphaphenylpropionitrile), which .azo compounds can 70 be prepared by the process disclosed by Alderson and Robertson in their U.-S. application Serial No. 136,586; 1,1-azodicyclopentanecarbonitrile,

which can be prepared by the process of Hartmann, Rec. trav. chim. 46 -153 (1927) Chem. weekblad 23-77-78, January 1926; alpha-(car- They can 'be used in stoichiometrically equivalent alpha,alpha'-azodiisobutyramide, which azo compounds can be Prepared by the process alpha,alpha' e azobis- (alpha methylcaprylonitrile), .alpha,alpha-' alpha,-

Ha CH3 Theseazo compounds -may be prepared by the general'procedures described-by Thiele and Stange, Ann. 283, 33-37 (1894); Robertson Serial No. 757,683; filed June 27, 1947; Thiele-and Heuser, Ann. 290, 1-4 3 (1896); Hartmann, Rec.

trav. chim. 46, 150-153 (1927); Chem. weekbl a'dr 23, 77-78, January 1926; Dox. J. A. C. S. 47, 1471-1477 (192-5); and Alderson and Robertson Serial No. 736,586, filed March 22, 1947. In the process of the Alderson and Robertson application Serial No. 736,586 the azine of an oxy carbonyl compound (aldehyde or ketone) of not more than 12 carbons is treated with an excess of hydrogen cyanide in a system containing not more than 50% water at room temperature or above. The resulting hydrazonitrile is then oxidized to the azonitrile by an oxidizing agent such as chloride or bromine in the presence of an acid such as hydrochloric acid. In the process of the Robertson application Serial No. 757,683 hydrogen cyanide is added to the semicarbazone of a ketone followed by oxidation of the resulting semicarbazodinitrile with potassium permanganate. This particular method is an improvement on the process of Thiele and Stange, loc. cit. The Alderson and Robertson application Serial No. 736,586, has issued as U. S. Patent 2,469,358.

These azo compounds can be used in proportions ranging from about 0.01% up to of the weight of the cycloalkene and halosilane in the reaction mixture. However, they are usually used in proportions ranging from about 0.5% to 3% of the weight of the reactants.

Although the azo compounds are the preferred type of catalyst for use in this reaction, other free radical-liberating compounds can be employed. Examples of these are the peroxygencontaining organic compounds, such as benzoyl peroxide, acetyl peroxide, tertiary-butyl hydroperoxide,- di-tertiary-amyl peroxide, tertiarybutyl-l-methylcyclohexyl peroxide, tertiarybutyl pentamethylethyl peroxide, di-tertiarybutyl peroxide, di-tertiary-butyl diperphthalate, and l-hydroxyethyl hydroperoxide-l. These peroxide catalysts are also used in small proportions based on the weight of the reactants, amounts ranging from 0.01% to 10% of the reactants being suitable. However when employing the peroxide type of catalyst in this reaction it is preferable that the reactants be heated in a glass vessel or glass-lined reaction vessel, since these catalysts are much less effective in stainless steel or silver-lined metal apparatus.

The cycloalkylhalosilanes of this invention, particularly icyclohexyltrichlorosilane, are particularly useful as chemical intermediate for the formation of siliconic acids which are in turn useful in the modification of synthetic resins.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations are to be understood therefrom. The invention is not limited to the exact-details; shown; and; described. or .v modifications will occur to those,;.skilled in aria.

iwhatclaimed is: Y A process for the preparat on or organs clohexanecarbgnitrile and group are attached to difierent carbon atoms which are non-aromatic, and at least one of which is tertiary, which tertiary carbon has further bonded to it through another carbon a negative substituent in which the three remaining valences of the latter carbon are satisfied by at least one element of atomic number 7 to 8.

3. A process for the preparation of organosilicon compounds wherein cyclohexene is heated at 60-1l5 C. for one to seventeen hours in the presence of an azo compound aliphatic in character wherein both valences of the acyclic azo, N=N, group are attached to difierent nonaromatic carbon atoms, at least one of which is tertiary and bonded to a cyano, CN, group with a halosilane having only halogen and hydrogen on the one silicon atom.

4. A process for the preparation of organosilicon compounds wherein a cycloalkene containing but one olefinic double bond is heated at 60-115" 0. for one to seventeen hours in the presence of an azo compound aliphatic in character wherein both valences of the acyclic azo, --N=N-, group are attached to different nonaromatic carbon atoms, at least one of which is tertiary and bonded to a cyano, -CN, group with a halosilane having only halogen and hydrogen on the one silicon atom.

5. A process for the preparation of organosilicon compounds wherein a cycloalkene containing but one olefinic double bond is heated at (SO- C. for one to seventeen hours with a halosilane having only halogen and hydrogen on the one silicon atom in the presence of a nonaromatic azo compound wherein both valences of the acyclic azo, -N=N--, group are attached to difierent tertiary carbons each attached to a cyano group, the azo compound containing only carbon, hydrogen, and the azo and cyano nitrogens.

6. A process for the preparation of organosilicon compounds wherein a cycloalkene containing but one olefinic double bond is heated at 60-115 0. for one to seventeen hours with a halosilane having only halogen and hydrogen on the one silicon atom'in the presence of a non-aromatic azo compound wherein both valences of the acyclic azo, N=N, group are attached to discrete monovalent cyanohydrocarbon radicals wherein the cyano group is on tertiary carbon mums;

from which stems the tree valence of the cyancr-f "UNITED' STATES PATENTS? hydrocarbon radical. r i Y N m Name Dat 7. A process for the preparation of organo- 2299 4 Vaughan Oct-h 20 2 silicon compounds wherein a cycloalkene cdn- 2324249 Vaughan July 3 taining but one olefinic double bondis heated at 5 Minr July 1945 60-115 C. for one to seventeen hours with a. halo- 2:405019 [331m "July 1946 silane having only halogen a hydrogen on the 2,40qi1s1 Scott Sept. 3 1946- one silicon atom in the presence of a-non-aro- 2,443,898 Emngboe June matic azo compound wherein both valences of 2 471 959 Hunt May 31 1949 the acyclic azo, --N=N-, group are attached to 1d 2524529 Krieble Oct 1950 discrete cyanoalkyl groups wherein the cyano """'*'j' zgroup is on tertiary carbon from which stems the OTHER REFERENCES :free valence of the cyanohydrocarbon radical. Summer: J. A. C. s., vol 69 (1947), page 188.

MAURICE LEON ERNSBERGER.- Burkhard: J. A. C. s., v01. 69 (1947), pages ROBERT DE WALD LIPSCOMB.- 16 2687-2689.

' 7 Barry: J. A. C. 8., vol. (1947), page 2916.

REFERENCES CITED 7 Pietrusza: J. A. c. s., vol. '10 (1948), pages The following references are of record in the 484-486. .i ile'of this patent: I i 1 Certificate of Correction Patent N 0. 2,570,463 October 9, 1951 MAURICE LEON FRNSBERGER ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 25, for sufficiently read suficient; column 5, line 30, for

chloride read chlorine; column 5. who 35, for semicarbazodinitrile read semicarbazidonitmle and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of January, A. D. 1952.

THOMAS F. MURPHY,

Assistant aommz'm'oner of Paton. 

1. A PROCESS FOR THE PREPARTION OF ORGANOSILICON COMPOUNDS WHEREIN CYCLOHEXANE IS HEATED FOR 13 HOURS AT A TEMPERATURE RISING FROM 75* C. TO 115* C. WITH TRICHLOROSILANE IN THE PRESENCE OF A MIXTURE OF ALPHA,ALPHA''-AZODIISOBUTYRONITRILE AND 1,1''-AZODICHLOHEXANECARBONITRILE AND CYCLOHEXYLTRICHLOROSILANE IS ISOLATED. 